Where Does Our Energy Come From?

by Preston McGill

You use electrical power for heating, cooling, cooking, refrigeration, light, sound, entertainment, computers, mobile devices and maybe even your car. Without power, life as we know it doesn’t exist.

Electrical power travels from the power plant to your house through an amazing system called the power distribution grid. The grid is quite public — if you live in a suburban or rural area, chances are it is right out in the open for all to see. It is so public, in fact, that you probably don’t even notice it anymore. Your brain likely ignores all of the power lines because it has seen them so often.

Although most of us take the power grid for granted, it’s anything but simple. There are 450,000 miles (724,205 kilometers) of high-voltage power lines and 160,000 miles (257,500 kilometers) of overhead transmission lines in the United States connecting electrical power plants to homes and businesses [source: DOE]. Since large amounts of energy cannot be stored, electricity must be produced as it is used [source: EIA]. The power distribution grid must respond quickly to shifting demand and continuously generate and route electricity to where it’s needed the most.

The power grid is also evolving. Upgrades in technology now let us connect our own home-generated electricity to the grid — using solar panels or wind generators — and get paid back by utilities. The U.S. federal government is also investing in a so-called smart grid that employs digital technology to more efficiently manage energy resources. The smart grid project also will extend the reach of the grid to access remote sources of renewable energy like geothermal power and wind farms.

Electrical power starts at the power plant. In almost all cases, the power plant consists of a spinning electrical generator. Something has to spin that generator — it might be a water wheel in a hydroelectric dam, a large diesel engine or a gas turbine. But in most cases, the thing spinning the generator is a steam turbine. The steam might be created by burning coal, oil or natural gas. Or the steam may come from a nuclear reactor.

Electricity generation is the single largest source of greenhouse gas emissions in the United States [source: EPA]. That’s why it’s so important to develop more renewable sources of energy. In 2014, 67 percent of America’s electricity came from fossil fuels like coal and natural gas. Hydroelectric energy was the largest renewable energy source, followed by solar, wind and geothermal power. In 2014, 6 percent of America’s electricity was produced by hydropower, while solar, wind and thermal energy together comprised another 5 percent [source: EIA].